The present discloses relates to an image forming apparatus such as a color printer.
A tandem type color printer is known which has a configuration where four photosensitive drums respectively for yellow, magenta, cyan, and black are integrally movable with respect to a body casing.
An example of a color printer of this kind includes four drum subunits in each of which a photosensitive drum is held by a frame. The four drum subunits are arranged at regular intervals in parallel between a pair of side plates. Front and rear beams are placed on both sides of the four drum subunits in the arrangement direction, respectively. The four drum subunits, the front beam, and the rear beam are collectively clamped by the pair of side plates, thereby configuring a drum unit which is movable with respect to a body casing.
When the drum unit is drawn out from the body casing in the arrangement direction of the photosensitive drums, the drum unit can be placed in a drawn-out position where the side above the drum unit is opened. When the drum unit is pushed from the drawn-out position into the body casing, the drum unit can be returned to a housing position in the body casing. In the state where the drum unit is drawn out to the drawn-out position, a developing cartridge can be attached to the drum unit.
A developing cartridge is attached into a space disposed on the front beam side of each of the drum subunits. The developing cartridge includes a developing roller. The developing roller has a developing roller shaft which is rotatably held by a case of the developing cartridge. Both end portions of the developing roller shaft are projected to the outside from the case of the developing cartridge.
Guide grooves for guiding attachment and detachment of the developing cartridge are formed in the inner surfaces of the side plates. When the developing cartridge is to be attached to the drum unit, the end portions of the developing roller shaft are inserted from the upper side into the guide grooves, and the developing cartridge is moved toward the drum unit so that the end portions are downward moved along the guide grooves. When the developing cartridge moves further and the developing roller is in contact with the photosensitive drum, the developing cartridge is restricted to move further. Thereafter, the developing cartridge is tilted toward the front beam about the developing roller shaft to complete the attachment of the developing cartridge to the drum unit.
A pressing projection is disposed in the developing cartridge. In the state where the developing cartridge is attached to the drum unit, the pressing projection is pressed from the upper side by a pressing/releasing mechanism disposed in the body casing. Therefore, the developing roller is pressingly contacted with the photosensitive drum by an adequate pressing force.
After the developing cartridge is attached to the drum unit, the drum unit is moved from the drawn-out position to the housing position in the body casing. At this time, in the case where the drum unit is vigorously moved toward the housing position, when the drum unit is located at the housing position, a large shock (reaction) is applied to the drum unit and the developing cartridge. There is a possibility that the developing cartridge may be detached from the drum unit by the shock.
An aspect of the disclosure is to provide an image forming apparatus in which it is possible to prevent a cartridge from being accidentally detached from an image forming position where an image forming operation is performed.
The aspect of the disclosure provides:
an image forming apparatus comprising:
a body;
a holding member configured to be movable between a housing position where the holding member is accommodated in the body, and a drawn-out position where the holding member is drawn out to an outside of the body;
a plurality of cartridges configured to be attached to the holding member along a attachment path, so that the plurality of cartridges are placed at image forming positions and are arranged in a movement direction of the holding member; and
a plurality of restricting members configured to be disposed correspondingly with the cartridges,
wherein in a state where the holding member is drawn out to the drawn-out position, the plurality of restricting members are located at unrestricted positions that are retracted from the attachment path,
wherein in an attachment process in which the holding member is moved from the drawn-out position to the housing position, the plurality of restricting members advance from the unrestricted positions to restricting positions on the attachment path to restrict the cartridges from being detached from the image forming positions.
In a state where the holding member is drawn out to the drawn-out position, moreover, the restricting member is retracted from the attachment path of the cartridge, and hence attachment and detachment of the cartridge to and from the holding member are not impeded.